Why so many carbs?

[t3rmin]

All part of the "hobby"..... think the guy crank starting the model T wished he had a electric starter??? Be proud, fix, and ride!!!! :-D :-D

Yeah yeah yeah... Except I haven't even gotten a chance to ride mine yet.:? I have a right to be bitter! :-D

[ghwrenchit]

Yeah yeah yeah... Except I haven't even gotten a chance to ride mine yet.:? I have a right to be bitter! :-D

Know the feeling man... what's left on the laundry list? Just make sure it's safe for the first ride, OK?

G

[Tnutz]

ha, gas in the oil...the ef was FULL...because of the dinosaur technology carbs..

[ghwrenchit]

ha, gas in the oil...the ef was FULL...because of the dinosaur technology carbs..

Dinosaur??? your prize GS is only 25yrs young.:-D Be proud, fix it, and ride. If things get the best of you put the tools down for a few days, especially the hammer.

G

[t3rmin]

Know the feeling man... what's left on the laundry list? Just make sure it's safe for the first ride, OK?

Well fortunately I'm (somewhat) patient. I've just replaced the ignition with a Dyna S, which I still need to permanently mount, route the wires, and adjust timing (but at least it's finally running!). Then I've got to clean the carbs 'cause I've got gas in the oil. Then I need to change the oil and put on a new valve cover gasket and half-moon seals. And I'm either almost out of gas or the petcock is bad, so I need to test that. And I guess the front brakes feel a bit squishy (although I'm not sure what it's supposed to feel like), so I may need to bleed 'em. Also I need to clean the air filter and re-seal the box with some weatherstripping tape (per forum advice).

*sigh* At least I've got a whole weekend ahead with which to bury myself in the bike. I'll have to convince the wife to bring my meals out to the garage. :-D

[ghwrenchit]

...I'll have to convince the wife to bring my meals out to the garage. :-D

No.... take the time to grill her the best steak she ever tasted. After that make her happy...It'll take 2 hours tops!!:-D :-D, then get back to the bike. H~ll, maker her happy on the bike... doesn't need to run. She may even offer to hand you wrench's after the fact, now it's becomes "OUR" project.\\/

G

[West]

A purely pragmatic approach:

If one carb and a manifold made any sense for cost reasons, you can bet your ass the engineers at the bike manufacturers would have figured out how to do it (On the orders of the bean counters). If it made any sense for performance reasons, you would have seen race bike's with 'em.

The only bike's that used one carb throat for multiple cylinders were a couple of old Triumphs and Harley's used them up until just recently. No suprise there - 'Harley, unimpeded by 75 years of progress'. I am sure there were a couple of others - maybe a Norton?

For all those who say 'carbs suck!, FI is great!', well, for about 100 years carbs were great, and FI was a f-in dream. You are taking some very difficult to develop technology for granted. FI is great no argument, but so is the Internet, and both were impossible for all of recorded history but the last 15 years or so.

[dpep]

New FI systems work better than our 25 year old carbs. I am curious how well those FI systems will be working 25 years from now. Will it be possible to repair them and if they can't be fixed will replacements be available? It will be 25 year old electronics technology by then. The carbs on our GSs will still be working like they do now and we will be able to service them the same as we do now.

I am not against progress. But I am always a little cautious about developments that take a part of my bikes functioning away from me and give it to a black box.

[jimcor]

The only bike's that used one carb throat for multiple cylinders were a couple of old Triumphs and Harley's used them up until just recently. No suprise there - 'Harley, unimpeded by 75 years of progress'. I am sure there were a couple of others - maybe a Norton?

Another engine that used a single carb to feed twin cylinders was the 300 Honda Dream. When the 305 Superhawk was unveiled it had twin carbs. These engines are relatively hard to tell apart visually, but according to an article I read years ago in one of the bike magazines (probably Cycle, but could have been Cycle World) they are two very different engines. Here is where memory fails me, but the author went into quite a bit of detail explaining the tuning of the Super Hawk engine and why a single carb would not work. So there are engine tuning considerations involved in a seperate carb for each cylinder, too.

[Clone]

Well, for me the benefit of multi-carbs I refer to my old Beetle. 1 carb for a 40hp 1200cc with a really long intake. The upgrade was to down-draft Webers, one for each bank of cylinders, shorter intake, better throttle response, easier tuning, increase in power.

So for me the multi-carb arrangement is to give more power from a smaller engine size. From breathability, response, mixture control. Ahm, that's all I got.

[Desolation Angel]

Wow. Everything anyone could ever want to know about carbs is in this one thread! :shock:

[Baatfam]

No parts to wear out like a carb, no synching...maybe a clogged injector someday....but thats about it....:-D technology! once you go efi you will never go back.

Agreed...I love EFI. As the cost has been going down, I see more and more drag cars going to EFI. Efficient, works great and you fine tune it with a lap top....

If there was an easy, low cost way to put a EFI system on my GS drag bike I would...heck, I'd consider it for my street GSes if it didn't cost more than the bike was worth....

I'm actually toying with the idea of adding EFI to my single cylinder, 500 BSA....just to do it.:-D

Later,
Bob T.

[flyingace]

New FI systems work better than our 25 year old carbs. I am curious how well those FI systems will be working 25 years from now. Will it be possible to repair them and if they can't be fixed will replacements be available? It will be 25 year old electronics technology by then. The carbs on our GSs will still be working like they do now and we will be able to service them the same as we do now.

I am not against progress. But I am always a little cautious about developments that take a part of my bikes functioning away from me and give it to a black box.

Good point. You'll probably have to stick a 50 year old carb on an EFI bike 25 years from now!

[Suzukizilla]

This is my take on the real reason single card over multi. The ole saying if it aint broke don’t fix it! They were putting these carbs on these bikes for years. Why reinvent the wheel? They create great upper end power and at that time fuel economy wasn’t an issue. That’s probably what riders were looking for in a bike at that time. It was a durable design that worked. A motorcycle company wasn’t going to go out on a limb to design something different and take a chance on it flopping. Especially during the GS’s life span where motorcycle competition was fierce. It’s also easier to be able to use the same carb and intake boot for a different bike that doesn’t have as much space where they might have to redesign a special intake for each model. Easier to just make a different air box. Just my opinion.

Oh and as far as intake on cars go (or bikes for that matter) the different size runner on an intake should be determined by what heads & cam you run. If you have large valve, large runners (on the head) and a cam that starts making power around 3k to 7k+ then you want an intake that is a tunnel ram or a single plane. Something that is not going to restrict flow. On the other hand if you want to make torque and your power band is in more of range of idle to 5k you want shorter/smaller runners to create a denser charge. Of coarse there are other factors like if it’s a straight or V or the size of the crank to determine how high a motor can rev but that’s to deep a subject to get into right now.

[Dan Ruddock]

The decision to put multi-carbs on our bikes was an easy one. At the state of tune these GS engines have, a single carb would work horribly. It could be designed to make good power but it would idle like a pop corn machine and would not be smooth at cruse speeds, get bad gas mileage, and would not pass emission tests of the day. Sounds like a hopped muscle car doesn't it. The problem is big cams create a situation where vacuum and intake pulses from one cylinder disturb the others and a accurate fuel mixture becomes impossible. With individual throats they are isolated from each other and each cylinder has its own mixture screw for accurate adjustment. Single carbs are fine for a mildly tuned car engine. I have tuned big V8's engines with multi weber carbs with big cams and they run fantastic, idle like glass and are as smooth as can be. Dan